Imaging apparatus

ABSTRACT

An image capture device that can shoot an image at a more appropriate exposure value with the image blur compensated for properly is provided. 
     The digital camera includes: a motion detecting section  34  for estimating a motion vector of an image shot; a blur compensating section for optically compensating for the blur of the image shot; a mode selecting section for selecting one of multiple control modes for the blur compensating section; and a setting determining section for determining a setting related to an exposure value for shooting an image based on the control mode selected by the mode selecting section and the motion vector estimated.

TECHNICAL FIELD

The present invention relates to an image capture device that can changethe shutter speeds of a mechanical shutter and/or an electronic shutter,and more particularly relates to an image capture device with an imagestabilizing function.

BACKGROUND ART

Recently, digital still cameras with an image stabilizing function havebeen developed and put on sale one after another. The image can bestabilized either by optically compensating for the blur of thesubject's image or by increasing the shutter speed with the sensitivityof the imager increased.

An image capture device with such a function is disclosed in PatentDocument No. 1. The device is designed to estimate the motion vector ofan image being shot and determine the shutter speed based on that motionvector. In this manner, the image blur caused by a motion of the subjectcan be reduced and the SNR of the image information can be increasedwhile an image of a still subject is being shot.

-   -   Patent Document No. 1: Japanese Patent Application Laid-Open        Publication No. 8-327917

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

However, it was discovered that if an image capture device with anoptical image stabilizing function that could be performed in any ofmultiple selectable control modes had its shutter speed adjustedaccording to the motion vector, some problems occurred.

More specifically, according to the image stabilizing control modeselected, the magnitudes of motion vectors estimated could be differenteven if the magnitude of shake of the image capture device was the same.It was discovered that if the exposure were adjusted in such a situationjust by the magnitude of motion vector, then an inappropriate exposurevalue could be selected for the magnitude of actual camera shake. Thatis to say, even if the image shot were not actually blurred so much, theexposure value could be unnecessarily small.

In order to overcome the problems described above, the present inventionhas an object of providing an image capture device that can shoot animage at a more appropriate exposure value with the image blurcompensated for properly.

Means for Solving the Problems

To achieve this object, an image capture device according to the presentinvention is designed to adjust an exposure value for shooting an image.The device includes: a motion detecting section for detecting a motionof an image shot; a blur compensating section for optically compensatingfor a blur of the image shot; a mode selecting section for selecting oneof multiple control modes for the blur compensating section; and asetting determining section for determining a setting related to anexposure value for shooting an image based on the control mode selectedby the mode selecting section and the motion of the image shot that hasbeen detected.

Then, the exposure value can be adjusted according to the control modeto perform the image stabilizing function. As a result, the problem withthe conventional device that may have an inappropriate exposure valueaccording to the image stabilizing function control mode can beovercome.

In one preferred embodiment, the image capture device of the presentinvention may be able to control an exposure value for shooting an imageby adjusting a shutter speed of a mechanical shutter and/or anelectronic shutter. In that case, the setting determining sectiondetermines the shutter speed based on the control mode selected and themotion of the image shot that has been detected.

Then, the shutter speed can be adjusted according to the control mode toperform the image stabilizing function. As a result, the problem withthe conventional device that may have an inappropriate exposure valueaccording to the image stabilizing function control mode can beovercome.

The control modes of the blur compensating section may include a firstcontrol mode and a second control mode. In the first control mode, theblur compensating section continues to compensate for the blur of theimage shot through a period from shooting one still picture to shootingthe next still picture. In the second control mode, a session that theblur compensating section either suspends or attenuates the operation ofcompensating for the blur of the image shot exists during the period.

In a situation where the motion of the image shot that has been detectedby the motion detecting section has a predetermined value, if thecontrol mode selected is the first control mode, the setting determiningsection may select a first setting as the exposure value. But if thecontrol mode selected is the second control mode, the settingdetermining section may select a second setting as the exposure value.In that case, the exposure value to shoot an image is greater when thesecond setting is selected than when the first setting is selected.

EFFECTS OF THE INVENTION

Thus, the present invention provides an image capture device that canshoot an image at a more appropriate exposure value with the image blurcompensated for properly.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration for a digitalcamera as a first preferred embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration for the motiondetecting section.

FIG. 3 schematically shows how to perform an image stabilizationoperation in MODE 1.

FIG. 4 schematically shows how to perform an image stabilizationoperation in MODE 2.

FIG. 5 is a schematic representation illustrating an exemplary menubeing displayed on the screen when an image stabilization control modeneeds to be selected.

FIG. 6 is a flowchart showing the shooting operation to be done by thedigital camera of the first preferred embodiment of the presentinvention.

FIG. 7 shows how the corrected shutter speed value changes with themagnitude of a motion vector.

DESCRIPTION OF REFERENCE NUMERALS

-   2 imager-   8 microprocessor-   9 operating section-   10 gyro sensor-   11 image stabilizer lens-   34 motion detecting section-   101 shutter control section-   104 compensation lens driving section

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 1. Configuration1-1. Overall Configuration

FIG. 1 is a block diagram illustrating a configuration for a digitalcamera according to the present invention. As shown in FIG. 1, thecamera includes a lens barrel 14, an imager 2, an image processingsection 3, and a microprocessor 8 for controlling the digital camera. Asthe imager 2, a CCD image sensor, a CMOS image sensor or an NMOS imagesensor may be used. The image processing section 3 and themicroprocessor 8 may be implemented as pieces of hardware with orwithout a software program installed for a microcomputer.

The lens barrel 14 includes an image stabilizer lens 11, a focus lens 12and an iris 13. The image stabilizer lens 11 can move within a planethat intersects with the optical axis of the lens barrel 14 at rightangles. Thus, by moving the image stabilizer lens 11 within that planeaccording to the magnitude of the camera shake, the blur of thesubject's image that has been produced on the imager 2 can becompensated for.

The imager 2 converts the image, which has entered the camera throughthe lens barrel, into an electrical signal (i.e., analog data). Next, anA/D converter 105 converts the electrical signal that has been generatedby the imager 2 into digital image data.

The image processing section 3 includes a preprocessing section 31, a YCconverting section 32, a compressing section 33, and a motion detectingsection 34. The preprocessing section 34 performs various types ofprocessing such as gain correction, gamma correction, white balancecorrection and flaw correction on the input digital image data that hascome from the A/D converter 105. The YC converting section 32 separatesthe preprocessed image data into a color difference signal and aluminance signal. The compressing section 33 subjects the YC convertedimage data to compression processing. Optionally, the compressingsection 33 may also have the function of expanding the compressed imagedata that has been read out from a memory card 7. A buffer memory 4 isused as a temporary work area to get these types of processing done. Thecompressed image data is written on the memory card 7 by way of a memorycard I/F 6. The images that are stored in the buffer memory 4 and thememory card 7 can be reproduced on an LCD monitor 5.

In accordance with a command entered through the operating section 9,the microprocessor 8 controls the overall system of this digital cameraincluding the image processing section 3, a shutter control section 101,an iris driving section 102 and a focus driving section 103. Also, basedon the magnitude of the camera shake that has been detected by a gyrosensor 10, the microprocessor 8 controls a compensation lens drivingsection 104 so as to minimize the blur of the subject's image that hasbeen produced on the imager 2.

1-2. Configuration for Motion Detecting Section

FIG. 2 is a block diagram illustrating a configuration for the motiondetecting section 34, which detects the motion of an image based on theimage data that has been generated by the imager 2. The motion detectingsection 34 includes a representative point storage section 341, acorrelation calculating section 342 and a motion vector estimatingsection 343.

The representative point storage section 341 divides the image signalrepresenting a current frame, which has been supplied from thepreprocessing section 31, into a plurality of areas and stores an imagesignal, associated with a particular representative point included ineach of those areas, as a representative point signal. Also, therepresentative point storage section 341 reads the representative pointof the previous frame that has already been stored and passes it to thecorrelation calculating section 342.

The correlation calculating section 342 gets the representative pointsignal of the previous frame from the representative point storagesection 341 and also gets the image data of the current frame from thepreprocessing section 31, and then calculates the degree of correlationbetween the representative point signal of the previous frame and theimage data of the current frame. This correlation calculation can bedone by comparing the difference between the representative point signalof the previous frame and the image signal of the current frame.Thereafter, the output of the correlation calculating section 342 isgiven to the motion vector estimating section 343.

Based on the result of calculation made by the correlation calculatingsection 342, the motion vector estimating section 343 estimates themotion vector between the previous and current frames of the image. Ifan image element that appeared in the previous frame has moved to adifferent location in the current frame, the motion vector representsthe magnitude and direction of that motion.

1-3. Modes of Optical Image Stabilization

The digital camera of this preferred embodiment has at least two modesfor controlling the image stabilization operation. That is to say, themicroprocessor 8 has at least two modes for controlling the compensationlens driving section 104. Hereinafter, those control modes will bedescribed with reference to FIGS. 3 and 4, which schematically show themodes for compensating for the image blur of the digital camera.

FIG. 3 shows the connection between the exposure state of the imager 2and the lens position instructed value, which is given by themicroprocessor 8 to the compensation lens driving section 104, in asituation where the microprocessor 8 is controlling the compensationlens driving section 104 in a control mode called “MODE 1”. Morespecifically, portion (a) of FIG. 3 shows how the lens positioninstructed value output by the microprocessor 8 changes with time.Portion (b) of FIG. 3 shows how the exposure state of the imager 2changes. And portion (c) of FIG. 3 shows the times of occurrence ofrespective events. In this example, the respective events and the timesare supposed to have the following correspondence. Specifically, theshutter release button is supposed to be pressed halfway at a time t11and pressed fully at a time t13, and then the imager 2 is supposed to besubjected to an exposure operation between the times t13 and t15. Asshown in FIG. 3, in the interval between a session of shooting one stillpicture and the next session of shooting another still picture, themicroprocessor 8 has the compensation lens driving section 104 continueto perform the operation of compensating for the blur of the image shot.Hereinafter, this control mode will be referred to herein as “MODE 1”.Although not shown in FIG. 1, the shutter release button forms part ofthe operating section 9.

By making the microprocessor 8 control the compensation lens drivingsection 104 in MODE 1, the image stabilization can be done even while astill picture is not being shot. For example, the image stabilizationcontrol can also be performed on a through-the-lens image for use todetermine the composition of a still picture. Also, in MODE 1, themicroprocessor 8 can drive the compensation lens driving section 104irrespective of the exposure state of the imager 2, and therefore, theimage stabilization operation can be controlled relatively easily.

FIG. 4 shows the connection between the exposure state of the imager 2and the lens position instructed value, which is given by themicroprocessor 8 to the compensation lens driving section 104, in asituation where the microprocessor 8 is controlling the compensationlens driving section 104 in a control mode called “MODE 2”. Morespecifically, portion (a) of FIG. 4 shows how the lens positioninstructed value output by the microprocessor 8 changes with time.Portion (b) of FIG. 4 shows how the exposure state of the imager 2changes. And portion (c) of FIG. 4 shows the times of occurrence ofrespective events. In this example, the respective events and the timesare supposed to have the following correspondence. Specifically, theshutter release button is supposed to be pressed halfway at a time t21and pressed fully at a time t23, and then the imager 2 is supposed to besubjected to an exposure operation between the times t24 and t25. Asshown in FIG. 4, in the interval between a session of shooting one stillpicture and the next session of shooting another still picture, thereexists period that the microprocessor 8 has the compensation lensdriving section 104 suspend the operation of compensating for the blurof the image shot. Hereinafter, this control mode will be referred toherein as “MODE 2”.

By making the microprocessor 8 control the compensation lens drivingsection 104 in MODE 2, the image stabilizer lens 11 is driven only whenit is necessary to do that to shoot a still picture. That is to say,since the image stabilizer lens 11 is not driven when it is notnecessary, the power that would otherwise be dissipated by thecompensation lens driving section 104 can be saved. As shown in FIG. 4,even during the interval between the times t23 and t24, the imagestabilization function is kept ON. This is done in order to perform theimage stabilization operation with good stability during the exposureperiod by performing the exposure operation after the imagestabilization function has been turned ON in advance. The imagestabilization function is not turned OFF right after the exposure periodis over. This is also done in order to perform the image stabilizationoperation with good stability during the exposure period. That is whywhen we say “the image stabilizer lens 11 is driven only when it isnecessary to do that to shoot a still picture”, the image stabilizationfunction is turned ON not only during the exposure period (i.e., fromthe time t24 through the time t25) but also during the pre-exposureperiod (i.e., from the time t23 through the time t24) and thepost-exposure period (i.e., from the time t25 on).

In MODE 2, other than the necessary control period (i.e., from the timet23 through the time t25) to shoot a still picture, the lens positioninstructed value is supposed to be constant. However, the presentinvention is in no way limited to that specific preferred embodiment.For example, the lens position instructed value other than the necessarycontrol period (i.e., from the time t23 through the time t25) to shoot astill picture may be smaller than the one during that necessary controlperiod (i.e., from the time t23 through the time t25) to shoot a stillpicture, and such a control mode may be used as a new control mode. Inshort, the present invention is applicable to any situation as long asthe microprocessor 8 has multiple modes for controlling the compensationlens driving section 104.

1-4. Correspondence Between this Preferred Embodiment and More GeneralConfiguration of the Present Invention

The digital camera of this preferred embodiment is an example of imagecapture device according to the present invention. Another image capturedevice according to the present invention could be a cellphone with acamera function, for example.

The motion detecting section 34 is an exemplary means for estimating amotion vector. The motion detecting section 34 may be implemented eitheras a DSP circuit dedicated for estimating a motion vector or by making ageneral-purpose computer execute a software program for motiondetection.

The gyro sensor 10, the microprocessor 8, the compensation lens drivingsection 104 and the image stabilizer lens 11 together form an exemplaryblur compensating means. Another blur compensating means may be providedby replacing the gyro sensor 10 with an angular velocity sensor, forexample. Also, although the camera shake is supposed to be compensatedfor by driving an inner lens in the preferred embodiment describedabove, the imager 2 may also be driven instead, or even the lens barrel14 may be driven in its entirety. In short, any other technique may beadopted as long as the blur of the subject's image can be compensatedfor optically.

The operating section 9 is an exemplary mode selecting means. Theoperating section 9 may be implemented as a piece of hardware such as abutton or a dial. Alternatively, the operating section 9 may also beimplemented by presenting characters or images on a screen with atouchscreen panel by software processing and allowing the user to make acontact with the screen. In that case, the operating section 9 isprovided as a combination of hardware and software. The microprocessor 8is an exemplary setting determining means.

2. Operation

Hereinafter, it will be described with reference to the accompanyingdrawings how the digital camera of this preferred embodiment operates.

2-1. Set Image Stabilization Mode

FIG. 5 is a schematic representation illustrating a menu being displayedon the LCD monitor 5 when an image stabilization control mode needs tobe selected for the digital camera. This menu 51 is displayed when theuser operates the operating section 9. On this menu 51, the user selectseither the field 52 representing MODE 1 or the field 53 representingMODE 2, thereby setting his or her desired image stabilization controlmode. This selection may be made using cross keys or ENTER button, whichform parts of the operating section 9. Also, the control mode currentlyselected may be stored in a flash memory in the microprocessor 8, forexample. Thus, the microprocessor 8 can know whether the control modecurrently selected is MODE 1 or MODE 2.

2-2. Shooting Operation

FIG. 6 is a flowchart showing the shooting operation to be done by thedigital camera.

First, the microprocessor 8 sees if the shutter release button has beenpressed halfway (in Step S1). In that case, before a still picture isshot, the LCD monitor 5 presents a through-the-lens image. By making theLCD monitor 5 present a through-the-lens image, the user can determinethe composition of the image to be shot while monitoring thethrough-the-lens image and can get the shooting operation done easily.The through-the-lens image is displayed on the LCD monitor 5 byperforming the following processing. Specifically, the imager 2 convertsthe optical signal, which has entered the camera through the lens barrel14, into an electrical signal. Then, the A/D converter 105 converts theelectrical signal into a digital signal. The image processing section 3subjects the digitized image data to preprocessing, YC conversion,electronic zoom processing and so on, thereby generating monitor imagedata. And when this monitor image data is input to the LCD monitor 5,the LCD monitor 5 presents a through-the-lens image. As used herein, the“through-the-lens image” refers to an image that will not be stored inthe memory card 7 eventually.

When the user presses halfway the shutter release button, which formspart of the operating section 9 (i.e., if the answer to the query ofStep S1 is YES), the microprocessor 8 performs AE processing and AFprocessing in parallel with each other in Step S2. In this preferredembodiment, the microprocessor 8 is supposed to perform the AEprocessing and the AF processing in parallel with each other. However,the present invention is in no way limited to this specific preferredembodiment. Alternatively, the microprocessor 8 may perform the AEprocessing and then the AF processing or perform the AF processing firstand then the AE processing.

During the AE processing, the microprocessor 8 determines the exposurevalue based on the image data that has been processed by the imageprocessing section 3. Then, the microprocessor 8 sets an appropriateshutter speed based on the exposure value. That is to say, themicroprocessor 8 sets the exposure period of the imager 2 according tothe exposure value. In this manner, the AE processing gets done by thedigital camera. It should be noted that the shutter speed that has beenset during the AE processing is a temporary setting. In a subsequentprocessing step, the microprocessor 8 will correct the shutter speedthat was set during the AE processing to determine the final shutterspeed.

In parallel with the AE processing, the microprocessor 8 adjusts theposition of the focus lens 12 according to the contrast value of theimage data that has been processed by the image processing section 3such that the contrast value becomes a peak value. Actually, the focuslens 12 is moved by the focus lens driving section 103 under the controlof the microprocessor 8. In this manner, the microprocessor 8 can getautofocusing processing done. That is to say, the AF processing alsogets done by the digital camera (in Step S2).

Next, the microprocessor 8 gets the motion vector of the image data fromthe image processing section 34 (in Step S3). More specifically, themicroprocessor 8 keeps getting motion vectors for a predetermined periodof time or more until the shutter release button is pressed fully.Alternatively, the microprocessor 8 may always get motion vectors, too.

Subsequently, when the user presses the shutter release button fully(i.e., if the answer to the query of Step S3 is YES), the microprocessor8 determines whether the image stabilization control mode currentlyselected is MODE 1 or MODE 2 (in Step S5). Also, the microprocessor 8calculates the average of the motion vectors that had been gotten duringthe predetermined period until the shutter release button was pressedfully. And this average is used as a motion vector magnitude forobtaining a corrected shutter speed value. In this preferred embodiment,the average of motion vectors that have been gotten during apredetermined period is supposed to be used as a motion vector magnitudefor obtaining a corrected shutter speed value. However, the presentinvention is in no way limited to this specific preferred embodiment.Alternatively, either the average of the absolute values, or the maximumvalue, of the motion vectors that have been gotten during thepredetermined period may also be used.

If the microprocessor 8 has determined that the control mode currentlyselected is MODE 1 (i.e., if the answer to the query of Step S5 is mode1), then the microprocessor 8 selects a method that uses a correctionvalue map #1 as a method for obtaining a corrected shutter speed value(in Step S9). The correction value map #1 will be described later.

On the other hand, if the microprocessor 8 has determined that thecontrol mode currently selected is MODE 2 (i.e., if the answer to thequery of Step S5 is mode 2), then the microprocessor 8 controls thecompensation lens driving section 104 to get an image stabilizationoperation started (in Step S6). More specifically, the microprocessor 8calculates the degree of camera shake of the digital camera based on theoutput of the gyro sensor 10. Then, the compensation lens drivingsection 104 shifts the image stabilizer lens 11 in such a direction thatcancels the camera shake under the control of the microprocessor 8.

Next, the microprocessor 8 determines whether or not the magnitude ofthe output of the gyro sensor 10 is greater than a predetermined value A(in Step S7). If the magnitude of the output of the gyro sensor 10 issmaller than the predetermined value A, then the microprocessor 8advances the control process to Step S9. On the other hand, if themagnitude of the output of the gyro sensor 10 is greater than thepredetermined value A, then the microprocessor 8 selects a method thatuses a correction value map #2 as a method for obtaining a correctedshutter speed value (in Step S8). The correction value map #2 will bedescribed later along with the correction value map #1.

Subsequently, the microprocessor 8 corrects the temporarily set shutterspeed in accordance with either the correction value map #1 selected inStep S9 or the correction value map #2 selected in Step S8, therebydetermining a final shutter speed value (in Step S10).

Next, the microprocessor 8 controls the imager 2 to get the exposureoperation started. Thereafter, the microprocessor 8 controls the imager2 and finishes the exposure operation when an exposure period,associated with the final shutter speed value, passes (in Step S11).Finally, the image processing section 3 subjects the image data capturedto a predetermined type of processing under the control of themicroprocessor 8, thereby writing processed image data on the memorycard 7 and ending the series of shooting operations (in Step S12).

2-3. Relation Between Vector and Shutter Speed

As described above, the microprocessor 8 determines the exposure valuebased on the image data that has been processed by the image processingsection 3 and then temporarily sets a shutter speed based on thatexposure value. In the digital camera of this preferred embodiment, themicroprocessor 8 corrects the temporarily set shutter speed based on themotion vector of the image data that has been processed by the imageprocessing section 3 and on the image stabilization control mode. Inthat case, the corrected shutter speed value is determined in eitherStep S8 or Step S9. Hereinafter, a method for determining the correctedshutter speed value will be described with reference to FIG. 7.

FIG. 7 shows a correlation between the motion vector, the imagestabilization control mode, and the corrected shutter speed value.

If the image stabilization control mode currently selected is MODE 1,then the microprocessor 8 corrects the shutter speed value in accordancewith the correction value map #1 shown in FIG. 7. That is to say, if themotion vector magnitude of the image data that has been processed by theimage processing section 3 is equal to or smaller than A1, themicroprocessor 8 selects SS1 as a corrected shutter speed value. On theother hand, if the motion vector magnitude is greater than A1 but equalto or smaller than A2, the microprocessor 8 selects SS2 as a correctedshutter speed value. Furthermore, if the motion vector magnitude isgreater than A2 but equal to or smaller than A3, the microprocessor 8selects SS3 as a corrected shutter speed value. And if the motion vectormagnitude is greater than A3, then the microprocessor 8 selects SS4 as acorrected shutter speed value.

Meanwhile, if the image stabilization control mode currently selected isMODE 2, then the microprocessor 8 corrects the shutter speed value inaccordance with the correction value map #2 shown in FIG. 7. That is tosay, if the motion vector magnitude of the image data that has beenprocessed by the image processing section 3 is equal to or smaller thanB1, the microprocessor 8 selects SS1 as a corrected shutter speed value.On the other hand, if the motion vector magnitude is greater than B1 butequal to or smaller than B2, the microprocessor 8 selects SS2 as acorrected shutter speed value. Furthermore, if the motion vectormagnitude is greater than B2 but equal to or smaller than B3, themicroprocessor 8 selects SS3 as a corrected shutter speed value. And ifthe motion vector magnitude is greater than B3, then the microprocessor8 selects SS4 as a corrected shutter speed value.

As shown in FIG. 7, if the motion vector magnitude is equal to orsmaller than A1, greater than B1 but equal to or smaller than A2,greater than B2 but equal to or smaller than A3, or greater than B3,then SS1, SS2, SS3 or SS4 is respectively selected, as the samecorrected shutter speed value for both MODE 1 and MODE 2. However, ifthe motion vector magnitude is greater than A1 but equal to or smallerthan B1, or greater than A2 but equal to or smaller than B2, or greaterthan A3 but equal to or smaller than B3, the corrected shutter speedvalues are different between MODE 1 and MODE 2. For example, if themotion vector magnitude is greater than A1 but equal to or smaller thanB1, then the microprocessor 8 determines SS2 and SS1 as correctedshutter speed values for MODE 1 and MODE 2, respectively. That is tosay, the final shutter speed for MODE 2 becomes lower than the one forMODE 1.

As described above, the microprocessor 8 controls the shutter controlsection 101 such that if the motion vector magnitude is equal to acertain value (i.e., greater than A1 but equal to or smaller than B1, orgreater than A2 but equal to or smaller than B2, or greater than A3 butequal to or smaller than B3 in this preferred embodiment), then theshutter speed for MODE 2 is lower than the one for MODE 1.

It should be noted that the present invention is applicable to any othersituation as long as there are multiple image stabilization controlmodes with motion vector magnitudes that will result in mutuallydifferent corrected shutter speed values. For example, the presentinvention is applicable to a situation where the corrected shutter speedvalues are different between those control modes in just a part of themotion vector magnitude range as in the preferred embodiment describedabove and to a situation where the corrected shutter speed values aredifferent between those control modes in the entire motion vectormagnitude range.

2-4. Specific Operation 2-4-1. In MODE 1

Hereinafter, it will be described with reference to FIGS. 3 and 6 howthe digital camera of this preferred embodiment operates if the imagestabilization mode is MODE 1.

Suppose the user presses the shutter release button halfway at a timet11 before starting shooting (in Step S1). In response, themicroprocessor 8 performs the AE processing and the AF processing.

Next, the microprocessor 8 obtains motion vectors from the imageprocessing section 3 (in Step S3) and continues getting them until theuser presses the button fully (in Step S4). And when the user pressesthe shutter release button fully at a time t13 (in Step S5), the processadvances to Step S9 in which the shutter speed is corrected. At thispoint in time, the microprocessor 8 retains the motion vectors, whichhave been estimated by the motion detecting section 34 between the timest12 and t13, in the internal memory. The microprocessor 8 calculates theaverage of those internally retained motion vectors and then defines theaverage as a motion vector magnitude for use to determine a correctedshutter speed value. Also, since the image stabilization control modecurrently selected is MODE 1, the microprocessor 8 obtains the correctedshutter speed value in accordance with the correction value map #1 shownin FIG. 7 (in Step S9). As the motion vector magnitude is obtained asdescribed above, the microprocessor 8 determines the corrected shutterspeed value based on that value and the relation shown in FIG. 7.Thereafter, the microprocessor 8 adds the corrected shutter speed valueto the shutter speed value that has been temporarily set in Step S2,thereby determining the final shutter speed. For example, in a situationwhere the shutter speed is selectable from ⅛ seconds, 1/15 seconds, 1/30seconds, or 1/60 seconds, if the temporarily set shutter speed is 1/15seconds and the corrected value should be one level higher than thetemporary one, then the final shutter speed becomes 1/30 seconds.

Thereafter, the imager 2 starts performing an exposure operation andcontinues the exposure for a period of time associated with the finalshutter speed, thereby obtaining captured image data (in Step S11).Then, the image processing section 3 subjects the captured image data topredetermined processing and then stores it in the memory card 7. Inthis manner, a series of shooting operations in MODE 1 gets done.

In the example described above, as soon as the shutter release button ispressed fully at the time t13, the exposure operation is supposed tostart immediately. However, there could be some time lag between thetime when the button is pressed fully and the time when the exposureoperation is started.

2-4-2. In MODE 2

Hereinafter, it will be described with reference to FIGS. 4 and 6 howthe digital camera of this preferred embodiment operates if the imagestabilization mode is MODE 2.

Suppose the user presses the shutter release button halfway at a timet21 before starting shooting (in Step S1). In response, themicroprocessor 8 performs the AE processing and the AF processing.

Next, the microprocessor 8 obtains motion vectors from the imageprocessing section 3 (in Step S3) and continues getting them until theuser presses the button fully (in Step S4). And when the user pressesthe shutter release button fully at a time t23 (in Step S5), themicroprocessor 8 starts performing an image stabilization control at thetime t23 (in Step S6). At this point in time, the microprocessor 8retains the motion vectors, which have been estimated by the motiondetecting section 34 between the times t22 and t23, in the internalmemory. The microprocessor 8 calculates the average of those internallyretained motion vectors and then defines the average as a motion vectormagnitude for use to determine a corrected shutter speed value.

Next, the microprocessor 8 determines whether or not the output of thegyro sensor 10 is greater than a predetermined value A. If the user isholding the digital camera with his or her hands, for example, thedigital camera has significant camera shake. In that case, the output ofthe gyro sensor 10 should be greater than the predetermined value A. Onthe other hand, if the digital camera is fixed on a tripod, for example,then the digital camera has little camera shake. In that case, theoutput of the gyro sensor 10 should be smaller than the predeterminedvalue A.

Supposing the output of the gyro sensor 10 is greater than thepredetermined value A, the microprocessor 8 obtains the correctedshutter speed value in accordance with the correction value map #2 shownin FIG. 1 (in Step S9). As the motion vector magnitude is obtained asdescribed above, the microprocessor 8 determines the corrected shutterspeed value based on that value and the relation shown in FIG. 7.Thereafter, the microprocessor 8 adds the corrected shutter speed valueto the shutter speed value that has been temporarily set in Step S2,thereby determining the final shutter speed (in Step S10).

On the other hand, if the output of the gyro sensor 10 is smaller thanthe predetermined value A, the microprocessor 8 obtains the correctedshutter speed value in accordance with the correction value map #1 shownin FIG. 7 (in Step S9). As the motion vector magnitude is obtained asdescribed above, the microprocessor 8 determines the corrected shutterspeed value based on that value and the relation shown in FIG. 7.Thereafter, the microprocessor 8 corrects the shutter speed value thathas been temporarily set in Step S2 with the corrected shutter speedvalue, thereby determining the final shutter speed (in Step S10).

After that, the shooting operation in MODE 2 is performed as in MODE 1.

2-5. Why Shutter Speed should be Decreased if Camera Shake isSignificant in MODE 2

As described above, if the image stabilization control mode is MODE 2,the image stabilizer lens 11 does not change its positions until justbefore a still picture starts to be shot (at the time t23), and theimage stabilization control is started after that time that is justbefore the shooting is started. That is why even if the magnitude of thecamera shake of the digital camera remains the same before and after thetime t23, the blur of the subject's image on the imager 2 has differentmagnitudes before and after the time t23.

According to the present invention, the corrected shutter speed isobtained based on the motion vector magnitude, which is the average ofthe motion vectors that have been estimated until just before a stillpicture starts to be shot. For that reason, there is no problem if themagnitude of the image blur during the exposure operation is similar tothat of the image blur while the motion vectors are being estimated.However, it is a problem if there is significant camera shake in MODE 2.That is to say, while motion vectors are being estimated, no imagestabilization control is performed, and therefore, there is significantimage blur. That is why if the shutter speed were corrected with amotion vector that has been estimated in such a state, then the shutterspeed would be just increased. However, since the image stabilizationcontrol is performed during the exposure operation, there is littleimage blur. That is why even if the shutter speed is not increased, animage can be shot with little blur. Therefore, if there is significantcamera shake in MODE 2, the magnitudes of image blur will be differentwhile the motion vectors are being estimated and while the exposureoperation is being performed. Consequently, if the shutter speed werejust corrected according to the motion vector magnitude estimated, thenthe shutter speed would be increased more than necessarily.

For that reason, if the camera shake is significant in MODE 2, theshutter speed is set based on the correction value map #2 that isdifferent from the one used in MODE 1. That is to say, themicroprocessor 8 controls the shutter control section 101 such that ifthe motion vector magnitude is equal to a certain value (i.e., greaterthan A1 but equal to or smaller than B1, or greater than A2 but equal toor smaller than B2, or greater than A3 but equal to or smaller than B3in this preferred embodiment), then the shutter speed for MODE 2 islower than the one for MODE 1.

On the other hand, if the camera shake is little, the magnitude of theimage blur remains the same even in MODE 2 just before and after theexposure operation (at the time t23). That is why the shutter speed isset based on the same correction value map as the one used in MODE 1.

Embodiment 2

The first preferred embodiment of the present invention described abovecould be modified in various manners as long as those modifications fallwithin the scope of the present invention. Those modified examples willbe described collectively as a second preferred embodiment of thepresent invention.

In the first preferred embodiment of the present invention describedabove, the exposure period of the imager 2 is supposed to be set usingan electronic shutter. However, the present invention is in no waylimited to that specific preferred embodiment. Alternatively, theexposure period may also be controlled by providing a mechanical shutterfor the imager 2 such that the mechanical shutter faces the subject andby adjusting the shutter speed of that mechanical shutter.

Also, in the first preferred embodiment of the present inventiondescribed above, two control modes called MODES 1 and 2 are supposed tobe used as the image stabilization control modes. However, the presentinvention is in no way limited to that specific preferred embodiment.For example, a third control mode may be further provided. In short,there may be a plurality of control modes in which the imagestabilization function is controlled differently.

Furthermore, in the first preferred embodiment of the present inventiondescribed above, a temporary shutter speed is supposed to be set andthen corrected. Alternatively, the shutter speed may also be determineddirectly based on the image stabilization mode, motion vector andexposure value.

Also, in the first preferred embodiment of the present inventiondescribed above, the AF processing is supposed to be performed in StepS2 shown in FIG. 6. Optionally, the present invention could also copewith a manual focus operation instead of performing the AF processing.

Furthermore, in the first preferred embodiment of the present inventiondescribed above, the motion of an image shot is supposed to be detectedby estimating a motion vector. However, the present invention is in noway limited to that specific preferred embodiment. Alternatively, themotion of an image shot can also be figured out by calculating thedifferences between the pixel values of the previous and next frames andintegrating them together. In any case, the present invention isapplicable to any situation as long as the motion of an image shot canbe calculated.

Optionally, in the first preferred embodiment of the present inventiondescribed above, the gain to the image data may be controlled accordingto the shutter speed value. For example, if the shutter speed is high, adark image may be brightened by increasing the gain. On the other hand,if the shutter speed is low, the noise of an image shot may be reducedby decreasing the gain. In the first preferred embodiment of the presentinvention, the image data that has been digitized by the preprocessingsection 31 may have its gain controlled. However, the present inventionis in no way limited to that specific preferred embodiment. For example,the image data as an analog signal may have its gain controlled beforepassed to the A/D converter 105.

INDUSTRIAL APPLICABILITY

The present invention is applicable for use in an image capture devicethat has multiple image stabilization control modes. Specifically, thepresent invention can be used effectively in a digital still camera or acellphone with a camera function, for example.

1. An image capture device with an ability to adjust an exposure valuefor shooting an image, the device comprising: a motion detecting sectionfor detecting a motion of an image shot; a blur compensating section foroptically compensating for a blur of the image shot; a mode selectingsection for selecting one of multiple control modes for the blurcompensating section; and a setting determining section for determininga setting related to an exposure value for shooting an image based onthe control mode selected by the mode selecting section and the motionof the image shot that has been detected, wherein the control modes ofthe blur compensating section include a first control mode and a secondcontrol mode, and wherein in the first control mode, the blurcompensating section continues to compensate the blur of the image shotthrough a period from shooting one still picture to shooting the nextstill picture, and wherein in the second control mode, a session thatthe blur compensating section either suspends or attenuates theoperation of compensating for the blur of the image shot during theperiod.
 2. The image capture device of claim 1, further comprising ashutter, wherein the device is able to control the exposure value forshooting an image by adjusting a shutter speed of the shutter, andwherein the setting determining section determines the shutter speedbased on the control mode selected and the motion of the image shot thathas been detected.
 3. (canceled)
 4. The image capture device of claim 1,wherein: in a situation where the motion of the image shot that has beendetected by the motion detecting section has at least one predeterminedvalue; the setting determining section selects a first setting as thesetting related to an exposure value if the control mode selected is thefirst control mode; the setting determining section selects a secondsetting as the setting related to an exposure value if the control modeselected is the second control mode; and the exposure value for shootingan image is greater when the second setting is selected than when thefirst setting is selected.
 5. The image capture device of claim 2,wherein the shutter is at least one of a mechanical shutter and anelectronic shutter.